1. Field of the Invention
The present invention relates to an insert-molded article, a production method of the insert-molded article, and an ink.
2. Description of the Related Art
Nowadays, insert-molded articles have come to be used, for example, in various indicator boards and housings of cellular phones, and display parts and operational parts of household electric appliances. In the production of these insert-molded articles, at the beginning, a decorative printing is made on the backside of a transparent film, generally for the purpose of protecting a printed layer, with a colored ink containing resin components such as polycarbonate, to be observed from the front side of the film. As the next step, the film on which the above-described decorative print layer is formed is processed into the surface shape of a molded article. Furthermore, the film having the surface shape of the above described molded article is inserted into a mold with the decorative print layer facing inside, then a melted resin is injected to the above described decorative print layer side, and the injected resin and the above described film are made to be integrated. An insert-molded article is thereby completed which is constituted with a transparent film, a decorative print layer and an injected resin, and in which printing is made so as the printed matter to be visually observable from the front surface side of the transparent film.
As described above, the production process of an insert-molded article is generally composed of the printing step, forming step and injection-molding step. It is an indispensable requirement in the printing step that <1> the adhesion between the film and the printed ink is sufficiently strong and the adhesion is maintained through the whole steps. Additionally, it is another indispensable requirement in the forming step that <2> the printed ink can be extended following the extension of the film caused by heating so that no crack and no exfoliation from the film occur. Additionally, it is another indispensable requirement in the injection-molding step that <3> the decorative print layer is not fluidized and swept away caused by the flow of the high temperature melted resin being injected, and <4> when the melted resin having been injected is cooled and solidified, the cooled and solidified resin and the ink on decorative print layer are made to strongly adhere to each other.
Any of these indispensable requirements <1> to <4> is a requirement of the ink for use in printing the decorative print layer. Accordingly, as the ink for use in printing the decorative print layer, inks have been proposed in which various types of polycarbonate resins are contained as the resin component (Japanese Patent Laid-Open No. 8-3502, Japanese Patent Laid-Open No. 2001-19885, Japanese Patent Laid-Open No. 2001-249793). However, even when the decorative print layer is formed by using the inks containing the polycarbonate resins as the resin component, the adhesion between the film and the ink involved in the indispensable requirement <1> can be obtained sufficiently in the case where the film to be printed contains polycarbonate, but the adhesion is not necessarily sufficient in the case where the printing film is made of polyethylene terephthalate, polyurethane or the like. Furthermore, as far as the indispensable requirements <2> to <4> are concerned, the interrelationship found between these requirements is such that when any one of these requirements is satisfied, the other requirements are not satisfied, and thus, it has been hardly possible to highly satisfy all the indispensable requirements <1> to <4>.
Accordingly, an object of the present invention is to provide an insert-molded article and a production method of the insert-molded article, which are able to highly satisfy all the requirements that become indispensable in the insert-molding. Additionally, another object of the present invention is to provide a various types of inks to be used for that purpose.